<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>弱类型</title>
</head>
<body>
    <script>
        var web = '弱类型';
        console.log(typeof web)  // string
        web = 99
        console.log(typeof web)  // number

        
        checkStress(item,index){
            this.checkIndex = index
        }
    </script>
</body>
</html>